The invention relates to a stop valve device between two part sections of a fluid connection which connects two fluid chambers of a vibration damper together, the stop valve device being constituted by at least one stop valve separating a high pressure part section and a low pressure part section, said stop valve being constituted by a stop valve body, and the stop valve body being adjustable by means of an external control between a shut-off position and an opening position.
Such stop valve devices are used in vibration dampers in a so-called by-pass duct which joins together two fluid chambers of the vibration damper. In the device the by-pass duct is divided by the stop valve into the low pressure part section and the high pressure part section. For example, such a by-pass duct may be found in twin-pipe vibration dampers between the fluid chamber through which the piston rod travels and the compensation chamber. In this case, on the opening of the stop valve, a flow through the by-pass duct takes place always in the same direction from the fluid chamber which receives the piston rod towards the compensation chamber, independently of the direction in which the piston rod may move relative to the cylinder. Through the shutting or the opening of the stop valve it is possible to alter the characteristic of the vibration damper. If the stop valve in the by-pass duct is open, the by-pass duct is switched substantially parallel with the piston valve arrangement, and the damping behaviour of the vibration damper is relatively mild. If the stop valve is closed, the damping characteristic of the vibration damper is essentially determined by the damping valve arrangement of the piston, and the damping behaviour of the vibration damper is relatively hard.